Mining machine



` Sept. zo, 1927.

' 1,643,220 R. B. METZNER MININGMACHINE Filed June 11. 1926 Sheets-Sheet 1 by the motor 18 driving pinion 16 andtherepA by the gear wheel l5, effecting alternate re- Y ciprocation of the connected pistons 8 and 29. The pistons 3 and 29 form the end vwalls of an intermediate chamber, the sidewalls of which are constituted by the cylinder 2. As

` the pistons 3 and 29 move forward `within the cylinder, the check valve 34C -ofpiston 29 `is opened and air is permitted to pass therethrough into the space between piston 29 and pistonV 28. `At the same time, the check valve 33 of piston-3 is seated, thereby compressing air between the pistons and 28, which body of compressed air causes the pis- Y ton 28 to advance with piston 3 and thereby impart to the rod 19 its: working stroke. Such body of compressed air` at the same time acts to cushion the piston 28 and prevent same from forcibly engaging the piston 3. Upon rearward movement of the piston 3, the valve 33 is unseated and the air compressed between the-pistons 3 and 28 escapes through `the port 39 inthe plug of said pis` ton 3.1 Since the piston 29 moves with the piston 3, the `valve 34is actuated to seat, following which theair between pistons 28 and 29 is compressed, therebyactuating the rod 19- to move rearwardly in its return stroke.

From the foregoing it will beseen that the 4 piston 28 and the thereto attached rod 19 the first piston, tie rods connecting said pair4 and the cutter 26 are actuated both onf the working and return stroke by the resilient bodies of air compressed between opposing faces of piston 28 and the pistons 3 and 29,

there being thus provided not only a mean' ofcushioning each end ofeach stroke of piston 28, but also `mea-ns for-cushioning the impact ofthe cutter.1 i. wWhat is claimedisi `l. In a mining machine, 4a cylinder having a tapered hollow extension on its for-V -ward end provided with air ports, a piston l inthe cylinder having a rod journaled inthe front end of the extension, a pair` of relatively spaced pistonson oppositesides of of pistons and freely movable through the -V first piston, a rod connected tothe rearmost of the pair of pistons, means to reciprocate `the rod, and checkvvalves carried by thepistons of said pair whereby,`upon reciprocation of Vsaid pair of pistons, `alternately, to i 1 i compress air between opposite facesof the V `first piston and for cushioning the lat-ter both first piston and the confronting faces of the pistons of the pair for edecting reciprocation of the `first piston and for cushioning the 'latter both on its advance and return strokes.

2. In combination with a cylinder, a pisp ton therein having a rod, a pair of pistons arranged on opposite sides of the first piston, tie rods rigidly connecting the pair of pistons and freely `movable through openings provided therefor in the first piston, a connectingrod attached to the rearmost of the pair `of pistons, means to reciprocate the connecting rod, and check valves carriedV i by the pistons of the pair whereby, upon reciprocation of said pair of pistons, alternately to compress air between opposite faces of the first piston andthe respective pistons of the pair for effecting reciprocation of the on its advance and return strokes.,

3; In a mining mach1ne,a` cylinder, a piston in the cylinder having a rod, a pairlofi relatively spaced pistonskdisposed Vonqop- Apositesides of the first piston, means to connect `the pair of pistons for movement in unison, reciprocating means-` for said: pair of pistons having connection with the rear piston of said pair, and check valves carried `by each of the pair of Vpistons wvhe'reby,

upon reciprocation thereof,air'will be com-` pressed between the opposed facesof the first piston and thev respective pistons of the pair for effecting reciprocation ofthe first `piston and for cushioning both of its strokes.

et. In a mining machine,a cylinder having a taperinghollow extension on its forward fend provided with air inlets,a piston in the upon reciprocationof the latter, air will be compressed between theV opposed faces of the V` first piston and the respective pistons. of the vpairfor effectingreciprocation ofthe first.`

piston and for cushioning each of the `strokes of the latter. l i 1 "In testimony whereof, I affix my signature.

v ROBERT B. METZNER. 

